It is known to provide a bed or box for a vehicle such as a pick-up truck. Typically, the bed is generally rectangular in shape to define a cargo area and is closed at the end by a tailgate. Traditional truck beds or boxes for pick-up trucks are constructed with a floor panel, several hat shaped cross sills mounted underneath for support of the floor panel, and inner side panels welded to the floor panel. At the front and rear corners of the bed, vertical reinforcements are welded to the floor panel and side panels to provide lateral stiffness and strength. The welding of the floor panel to bottom edges of the inner side panels involves a structural discontinuity, which in some service conditions, become highly stressed so that it may require additional reinforcement.
It is also known to hydroform tubular components or members. Hydroformed tubular members are becoming increasingly popular in automotive body structural applications. During vehicle body manufacturing, many of the hydroformed tubular members are used in vehicle body and chassis applications. However, vehicle strength, stiffness, and/or impactworthiness often necessitate the need for local areas of structural reinforcement to meet their design goals.
A method to improve the rigidity of the pick-up truck bed or box has been proposed in which two U-shaped hydroformed tubular cross sills are to replace all the hat shaped roll formed parts and all the reinforcements around the stake post areas. With this proposal, it often requires extensive hydroforming tool and equipment investments to hydroform U-shaped tubular sills and significant changes in the existing assembly process sequence.
As a result, it is desirable to provide a new cross sill construction for a bed or box of a vehicle. It is also desirable to provide a new cross sill construction that takes advantage of unique characteristics and cost-effectiveness associated with hydroforming and roll-forming processes. It is further desirable to provide a new method of making a cross-sill construction for a bed or box of a vehicle. Therefore, there is a need in the art to provide a new cross sill assembly and method of making same that meets these desires.